diff --git a/PLAN.md b/PLAN.md
index 01edc1d..93df4e3 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -122,6 +122,7 @@ All package manifests, lockfiles, configuration, documentation, licences, CI, an
 | 8 | GitHub Pages and domain preparation | Produce strict static output for every included route and asset, add a pinned least-privilege Pages workflow for protected `main`, and prepare domain-root metadata for `link42.app`. Repository Pages settings, custom-domain APIs, DNS, DigitalOcean, and production verification remain excluded. | 7 | done |
 | 9 | Faithful public homepage migration | Correct the public homepage and shell to match the pinned public-facing source: original copy, section order, visual structure, theme behaviour, and public header/footer presentation. Keep only public surfaces; exclude auth, sessions, API routes, and private runtime/deployment code. | 1, 2, 4, 5 | done |
 | 10 | Open-source hosting and feedback guidance | Publish a dedicated page covering repository and site hosting, the actual technology used by the website and Rule1, public bug and suggestion routes, and private security reporting; align site navigation and verification with the new route. | 9 | done |
+| 11 | Secondary navigation alignment | Centre the secondary navigation link group on desktop and tablet while retaining left-aligned horizontal scrolling and first-link reachability on mobile. | 10 | done |
 
 One completed feature equals one tested commit and push. Do not start the next feature with uncommitted work.
 
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index 9660669..84a42e3 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -30,9 +30,9 @@ let { children } = $props();
 <style>
   .page { display: flex; flex-direction: column; min-height: 100vh; }
   .site-nav { background: var(--bg); border-bottom: 1px solid var(--border); }
-  .site-nav-inner { display: flex; gap: 24px; max-width: 1200px; padding: 0 24px; margin: 0 auto; }
+  .site-nav-inner { display: flex; justify-content: center; gap: 24px; max-width: 1200px; padding: 0 24px; margin: 0 auto; }
   .site-nav a { padding: 10px 0; color: var(--text-mid); font-size: 13px; text-decoration: none; border-bottom: 2px solid transparent; }
   .site-nav a:hover { color: var(--text); }
   .site-nav a.active { color: var(--text); font-weight: 600; border-bottom-color: var(--text); }
-  @media (max-width: 640px) { .site-nav-inner { gap: 16px; padding: 0 16px; overflow-x: auto; } .site-nav a { flex: 0 0 auto; } }
+  @media (max-width: 640px) { .site-nav-inner { justify-content: flex-start; gap: 16px; padding: 0 16px; overflow-x: auto; } .site-nav a { flex: 0 0 auto; } }
 </style>
diff --git a/tests/e2e/shell.spec.ts b/tests/e2e/shell.spec.ts
index 591257e..7843404 100644
--- a/tests/e2e/shell.spec.ts
+++ b/tests/e2e/shell.spec.ts
@@ -65,6 +65,40 @@ test("theme switch is labelled and persists", async ({ page }, testInfo) => {
   expect(accessibility.violations).toEqual([]);
 });
 
+test("secondary navigation is centred on desktop and reachable on mobile", async ({ page }, testInfo) => {
+  const isMobile = testInfo.project.name.startsWith("mobile-");
+  if (isMobile) {
+    await page.setViewportSize({ width: 320, height: 812 });
+  }
+
+  await page.goto("/about");
+  const navigation = page.getByRole("navigation", { name: "Site navigation" });
+  const navigationInner = navigation.locator(".site-nav-inner");
+  const links = navigation.getByRole("link");
+
+  if (isMobile) {
+    const firstLink = links.first();
+    const firstLinkBox = await firstLink.boundingBox();
+    expect(firstLinkBox).not.toBeNull();
+    expect(firstLinkBox?.x).toBeCloseTo(16, 0);
+    await expect(navigationInner).toHaveCSS("justify-content", "flex-start");
+    await expect(navigationInner).toHaveCSS("overflow-x", "auto");
+    expect(await navigationInner.evaluate((element) => element.scrollWidth)).toBeGreaterThan(
+      await navigationInner.evaluate((element) => element.clientWidth),
+    );
+  } else {
+    const firstLinkBox = await links.first().boundingBox();
+    const lastLinkBox = await links.last().boundingBox();
+    expect(firstLinkBox).not.toBeNull();
+    expect(lastLinkBox).not.toBeNull();
+    const groupCentre = ((firstLinkBox?.x ?? 0) + (lastLinkBox?.x ?? 0) + (lastLinkBox?.width ?? 0)) / 2;
+    expect(groupCentre).toBeCloseTo(640, 0);
+    await expect(navigationInner).toHaveCSS("justify-content", "center");
+  }
+
+  await expectNoHorizontalOverflow(page);
+});
+
 test("skip link reaches main content", async ({ page }) => {
   await page.goto("/");
   await page.keyboard.press("Tab");